Coating, preparation method and application thereof, and coated product

Abstract

The invention discloses a coating as well as a preparation method and application thereof and a coated product. The epoxy resin is cured by using the phthalonitrile resin, so that the stability, the high temperature resistance, the corrosion resistance and the adhesive property of the coating can be remarkably improved, and the application requirements in extremely severe environments such as high humidity, high heat and the like can be met. The end group of the phthalonitrile resin contains cyano (C-N), nitrogen atoms on the cyano (C-N) can react with epoxy groups of the epoxy resin through nucleophilic attack to form a highly crosslinked polymer network, and the crosslinked network endows the coating with excellent thermal stability; a large number of benzene ring components in the molecular structure of the phthalonitrile resin endow the phthalonitrile resin with excellent heat resistance, excellent temperature resistance can be provided for a final coating, and the processability of the phthalonitrile resin is improved due to the flexibility characteristic of ether bonds.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a coating, a preparation method and application thereof, and a coated product. Background Art

[0002] Epoxy resin is an important thermosetting resin with good comprehensive properties, including excellent mechanical properties, electrical insulation properties, chemical resistance and adhesion, which also makes it widely used in coatings, adhesives, electronic device packaging, aerospace, microelectronic materials and other fields.

[0003] Epoxy resin coating is a liquid or solid coating composed of epoxy resin, curing agent, toughening agent, accelerator, diluent, filler, stabilizer, coupling agent and other additives. Among them, epoxy resin and curing agent are essential components. Epoxy resin coating also stands out among many coatings with its good comprehensive performance and wide applicability. However, epoxy resin coating cured with ordinary curing agent has insufficient high temperature resistance and low mechanical strength, which makes it difficult to meet its application in extremely harsh environments such as high humidity and high heat.

[0004] Therefore, it is an urgent problem to provide a coating material that can be used in extremely harsh environments such as high humidity and high heat, has good adhesion and stability, excellent corrosion resistance and high temperature resistance. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a coating and a preparation method and application thereof, and a coated product, aiming to solve the problem that epoxy resin coatings cured by common curing agents are difficult to meet the application requirements of extremely harsh environments such as high humidity and high heat.

[0006] The embodiment of the first aspect of the present invention provides a coating, wherein the raw material components of the coating include, by weight: 70 to 240 parts of epoxy resin composition and 10 to 100 parts of phthalonitrile resin;

[0007] The epoxy resin composition comprises 20 to 100 parts of bisphenol A epoxy resin, 10 to 40 parts of novolac epoxy resin, and 40 to 100 parts of hyperbranched epoxy resin;

[0008] The phthalonitrile resin is selected from at least one of bisphenol A phthalonitrile resin, isophthalonitrile phthalonitrile resin and liquid phthalonitrile resin.

[0009] According to the coating of the embodiment of the first aspect of the present invention, at least the following beneficial effects are achieved: the coating provided by the present invention, by curing epoxy resin with phthalonitrile resin, can significantly improve the high temperature resistance, corrosion resistance and bonding performance of the coating: on the one hand, the phthalonitrile resin end group contains cyano (CN), and the nitrogen atom thereon can react with the epoxy group of the epoxy resin through nucleophilic attack, and a three-dimensional cross-linked thermosetting epoxy resin can be obtained after the epoxy group is ring-opened; on the other hand, a large number of benzene ring components in the molecular structure of the phthalonitrile resin give it excellent heat resistance, which can provide excellent heat resistance for the final coating, and the flexible characteristics of the ether bond also improve its processing performance. Using phthalonitrile resin as a curing agent for epoxy resin, phthalonitrile can effectively react with the epoxy group to form a highly cross-linked polymer network, and this cross-linked network gives the coating excellent thermal stability, which will greatly improve the performance of the obtained epoxy resin coating under high temperature environment. Moreover, in the coating component, the epoxy resin is obtained by a reasonable ratio of bisphenol A epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin, which can increase the crosslinking degree of the resin and thus improve the thermal stability of the resin. Therefore, the present invention uses phthalonitrile resin to cure the epoxy resin, which can significantly improve the corrosion resistance and high temperature resistance of the coating, and the coating has good adhesion and stability, which can meet the application requirements of extremely harsh environments such as high humidity and high heat.

[0010] In some embodiments of the present invention, the raw material components of the coating include, by weight: 105-185 parts of epoxy resin composition and 30-50 parts of phthalonitrile resin.

[0011] In some embodiments of the present invention, the epoxy resin composition comprises, by weight, 50 to 100 parts of bisphenol A epoxy resin, 15 to 35 parts of novolac epoxy resin and 40 to 50 parts of hyperbranched epoxy resin.

[0012] In some embodiments of the present invention, the bisphenol A type phthalonitrile resin is obtained by copolymerization of bisphenol A type phthalonitrile monomer, and the structural formula of the bisphenol A type phthalonitrile monomer is:

[0013]

[0014] In some embodiments of the present invention, the isophthalonitrile resin is obtained by copolymerization of isophthalonitrile monomers, and the structural formula of the isophthalonitrile monomers is:

[0015]

[0016] In some embodiments of the present invention, the liquid phthalonitrile resin is obtained by copolymerization of liquid phthalonitrile monomers, and the structural formula of the liquid phthalonitrile monomers is:

[0017]

[0018] In some embodiments of the present invention, the bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, E20 epoxy resin and E12 epoxy resin.

[0019] In some embodiments of the present invention, the novolac epoxy resin is selected from at least one of F51 epoxy resin and NPCN-704 epoxy resin.

[0020] In some embodiments of the present invention, the hyperbranched epoxy resin is selected from at least one of AFG-90 epoxy resin, AFG-90H epoxy resin, AG-80 epoxy resin, AG-70 epoxy resin, AG-601 epoxy resin and AG-602 epoxy resin.

[0021] In some embodiments of the present invention, the raw material components of the coating further include: 0.1 to 100 parts of filler, by weight.

[0022] In some embodiments of the present invention, the filler is selected from at least one of carbon black, graphite, carbon nanotubes, activated carbon, alumina, silica, mica, boron nitride, calcium silicate, benzoin, titanium dioxide, MXene, glass microspheres, quartz sand, iron powder, iron salt, cobalt chloride, nickel chloride, iron oxide, ferrous oxide, cobalt oxide, nickel oxide, sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate, and calcium phosphate.

[0023] The embodiment of the second aspect of the present invention provides a method for preparing the coating as described above, comprising the steps of: mixing the raw materials according to weight components, heating and curing, and grinding and screening to obtain epoxy resin sintered powder.

[0024] The preparation method according to the embodiment of the second aspect of the present invention has at least the following beneficial effects: the preparation method of the coating provided by the present invention has a simple process, mild reaction conditions, easy operation, high production efficiency, and is suitable for large-scale production applications.

[0025] In some embodiments of the present invention, the heating and curing process is: heating to 100-280° C. and curing for 15-60 minutes.

[0026] In some embodiments of the present invention, the heating curing process is gradient temperature rise curing, which includes two stages: heating to 100-230° C. for curing for 15-30 min, and then heating to 230-280° C. for curing for 15-30 min.

[0027] An embodiment of the third aspect of the present invention provides the use of the coating as described above or the coating prepared by the preparation method as described above in coating of a metal substrate.

[0028] According to the application of the third aspect of the embodiment of the present invention, there are at least the following beneficial effects: the present invention applies the obtained coating to the coating of the metal substrate, and the formed coating has the characteristics of high density, good adhesion to the metal substrate, and good tolerance in high humidity and high heat environment, which can meet the application requirements of complex, harsh and extreme environments such as high humidity and high heat.

[0029] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy.

[0030] An embodiment of the fourth aspect of the present invention provides an anti-corrosion coating, wherein the coating as described above or the coating prepared by the preparation method as described above is uniformly coated on the surface of a metal substrate, and the anti-corrosion coating is obtained after curing.

[0031] The anti-corrosion coating according to the fourth aspect of the embodiment of the present invention has at least the following beneficial effects: the present invention applies the above-mentioned coating to a metal substrate, and the formed coating has the characteristics of high density, good adhesion to the metal substrate, and good tolerance in high humidity and high heat environments, and can meet the application requirements of complex, harsh and extreme environments such as high humidity and high heat.

[0032] An embodiment of the fifth aspect of the present invention provides a coated product, comprising a metal substrate and the coating as described above or the coating prepared by the preparation method as described above, coated on the metal substrate.

[0033] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy.

[0034] An embodiment of the sixth aspect of the present invention provides the use of the above-mentioned coating or the above-mentioned anti-corrosion coating in the fields of home appliance manufacturing, aerospace, and automobile manufacturing.

[0035] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0037] Figure 1 is a DSC spectrum of the epoxy resin prepolymer before curing in Example 1 of the present invention;

[0038] Figure 2This is a DSC spectrum of the epoxy resin coating cured by curing the phthalonitrile resin in Example 1 of the present invention;

[0039] Figure 3 FTIR spectrum of the epoxy resin prepolymer before curing in Example 1 of the present invention;

[0040] Figure 4 This is the FTIR spectrum of the epoxy resin coating cured by curing the phthalonitrile resin in Example 1 of the present invention;

[0041] Figure 5 is a TGA curve of the epoxy resin coating cured by curing the phthalonitrile resin in Example 1 of the present invention in an air atmosphere;

[0042] Figure 6 This is the TGA curve of the epoxy resin coating cured by curing the phthalonitrile resin in Example 1 of the present invention under an argon atmosphere. DETAILED DESCRIPTION

[0043] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0044] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0045] In the description of the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. Unless otherwise specified, each reaction or operation step may be performed in sequence or not. Preferably, the reaction method of the present invention is performed in sequence.

[0046] If no specific techniques or conditions are specified in the following examples, the techniques or conditions described in the literature in the art or the product instructions are used. All reagents or instruments without manufacturer specified are conventional products that can be purchased commercially.

[0047] The first aspect of the present invention provides a coating, wherein the raw material components of the coating include, by weight, 70 to 240 parts of an epoxy resin composition and 10 to 100 parts of a phthalonitrile resin; wherein the epoxy resin composition includes 20 to 100 parts of a bisphenol A epoxy resin, 10 to 40 parts of a novolac epoxy resin, and 40 to 100 parts of a hyperbranched epoxy resin; and the phthalonitrile resin is selected from at least one of a bisphenol A phthalonitrile resin, an isophthalic phthalonitrile resin, and a liquid phthalonitrile resin.

[0048] The coating provided by the present invention utilizes phthalonitrile resin to cure epoxy resin, which can significantly improve the ablation resistance, high temperature performance, corrosion resistance and bonding performance of the coating: on the one hand, the phthalonitrile resin end group contains cyano (CN), and the nitrogen atom thereon can react with the epoxy group of the epoxy resin through nucleophilic attack, and the epoxy group can obtain a three-dimensional cross-linked thermosetting epoxy resin after ring opening; on the other hand, a large number of benzene ring components in the molecular structure of the phthalonitrile resin give it excellent heat resistance, which can provide excellent heat resistance for the final coating, and the flexible characteristics of the ether bond also improve its processing performance. Using phthalonitrile resin as a curing agent for epoxy resin will greatly improve the performance of the obtained epoxy resin coating under high temperature environment. Moreover, in the coating component, the epoxy resin is obtained by reasonable proportioning of bisphenol A epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin, which can increase the crosslinking degree of the resin and thus improve the thermal stability of the resin. Therefore, the present invention uses phthalonitrile resin to cure epoxy resin, which can significantly improve the corrosion resistance and high temperature resistance of the coating. The coating has good adhesion and stability, ablation resistance, corrosion resistance and bonding performance, and can meet the application requirements of extremely harsh environments such as high humidity, high heat, and ablation resistance.

[0049] In some embodiments of the present invention, the raw material components of the coating include, by weight: 105 to 185 parts of the epoxy resin composition and 30 to 50 parts of the phthalonitrile resin.

[0050] In some embodiments of the present invention, the phthalonitrile resin is selected from at least one of bisphenol A type phthalonitrile resin, isophthalic phthalonitrile resin and liquid phthalonitrile resin. Phthalonitrile resin is a general term for a class of thermosetting resins terminated with phthalonitrile structure, and the aromatic heterocyclic body network structure formed after curing gives the phthalonitrile resin excellent thermal stability, chemical corrosion resistance, flame retardancy, low dielectric constant, etc. The above-mentioned phthalonitrile resin end group contains cyano (CN), which can react with the epoxy group of epoxy resin, and a large number of benzene rings in the molecular structure can provide suitable temperature resistance for the final coating material, and the flexible characteristics of the ether bond also improve its processing performance.

[0051] In some embodiments of the present invention, the bisphenol A type phthalonitrile resin is obtained by copolymerizing bisphenol A type phthalonitrile monomers, and the structural formula of the bisphenol A type phthalonitrile monomer is:

[0052]

[0053] In some embodiments of the present invention, the bisphenol A-type phthalonitrile resin can be purchased directly or prepared according to conventional techniques in the art.

[0054] In some embodiments of the present invention, the isophthalonitrile resin is obtained by copolymerizing isophthalonitrile monomers, and the structural formula of the isophthalonitrile monomers is:

[0055]

[0056] In some embodiments of the present invention, the above-mentioned isophthalonitrile phthalonitrile resin can be purchased directly or prepared according to conventional techniques in the art. For example, it can be prepared according to the methods in the literature [KELLER TM, DOMINGUEZ DD. High temperature resorcinol-based phthalonitrile polymer [J]. Polymer, 2005, 46 (13): 4614-4618] and [ZHOU H, BADASHAH A, LUO ZH, et al. Preparation and property comparison of ortho, meta, and para autocatalytic phthalonitrile compounds with amino group [J]. Polymers for Advanced Technologies, 2011, 22(10): 1459–1465.] The synthesized 4-amino-(3,4-dicyanophenoxy)benzene (SCP) is catalytically cured to obtain the above-mentioned isophthalonitrile monomer (i.e., 1,3-bis(3,4-dicyanophenoxy)benzene (PN)), wherein the preparation method comprises: mixing the PN monomer with 5 wt% of the SCP curing agent powder, and then heating and dissolving the mixture in acetone at a mass ratio of 1:3 at 70°C to form a clear and uniform isophthalonitrile resin solution.

[0057] In some embodiments of the present invention, the liquid phthalonitrile resin is obtained by copolymerization of liquid phthalonitrile monomers, and the structural formula of the liquid phthalonitrile monomers is:

[0058]

[0059] In some embodiments of the present invention, the liquid phthalonitrile resin can be purchased directly or prepared according to conventional techniques in the art.

[0060] In other embodiments of the present invention, the phthalonitrile resin may be a resin including a cyano group (CN), an ether bond, and a benzene ring, but is not limited thereto.

[0061] In some embodiments of the present invention, the epoxy resin composition includes, by weight, 50 to 100 parts of bisphenol A epoxy resin, 15 to 35 parts of novolac epoxy resin, and 40 to 50 parts of hyperbranched epoxy resin.

[0062] In some embodiments of the present invention, the bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, E20 epoxy resin and E12 epoxy resin, but is not limited thereto, and may also be selected from common types in the art.

[0063] In some embodiments of the present invention, the phenolic epoxy resin is selected from at least one of F51 epoxy resin and NPCN-704 epoxy resin, but is not limited thereto, and may also be selected from common types in the art.

[0064] In some embodiments of the present invention, the hyperbranched epoxy resin is selected from at least one of AFG-90 epoxy resin, AFG-90H epoxy resin, AG-80 epoxy resin, AG-70 epoxy resin, AG-601 epoxy resin and AG-602 epoxy resin, but is not limited thereto and can also be selected from common models in the art.

[0065] In some embodiments of the present invention, the raw material components of the coating further include: 0.1 to 100 parts of filler, preferably 0.1 to 10 parts by weight.

[0066] In some embodiments of the present invention, the filler is selected from at least one of carbon black, graphite, carbon nanotubes, activated carbon, aluminum oxide, silicon dioxide, mica, boron nitride, calcium silicate, benzoin, titanium dioxide, MXene, glass microspheres, quartz sand, iron powder, iron salt, cobalt chloride, nickel chloride, ferric oxide, ferrous oxide, cobalt oxide, nickel oxide, sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate and calcium phosphate, preferably benzoin (benzoyl alcohol ketone). The addition of fillers can be used to regulate the bonding force of the resin adhesive, and / or high temperature resistance, and / or give the material other known excellent properties, and / or control costs. For example, benzoin in the filler can be used as a defoaming agent, silicon dioxide or aluminum oxide can be used as a reinforcing agent and a cost-reducing agent, and sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate or calcium phosphate can be used as a rust remover. In the present invention, the raw material components of the coating may also include other additives, such as defoamers, leveling agents, thixotropic agents, coupling agents, anti-settling agents, dispersants, etc., and the above-mentioned defoamers, leveling agents, thixotropic agents, coupling agents, anti-settling agents, dispersants, etc. can be reasonably selected from any common types in the art according to actual conditions, and no limitation is made here.

[0067] The second aspect of the present invention provides a method for preparing the above-mentioned coating, comprising the steps of: mixing the raw materials according to weight components, heating and curing, and grinding and screening to obtain epoxy resin sintered powder.

[0068] The coating preparation method provided by the invention has simple process, mild reaction conditions, easy operation, high production efficiency and is suitable for large-scale production application.

[0069] In some embodiments of the present invention, the heating and curing process is: heating to 100-280° C. and curing for 15-60 minutes.

[0070] In some embodiments of the present invention, the heating curing process is gradient temperature curing, which includes two stages: heating to 100-230° C. for curing for 15-30 min, and then heating to 230-280° C. for curing for 15-30 min.

[0071] In some preferred embodiments of the present invention, the heating curing process is gradient temperature rise curing, which includes two stages: heating to 100-230° C. for curing for 15 min, and then heating to 230-280° C. for curing for 15 min.

[0072] In some embodiments of the present invention, after the epoxy resin sintered powder is obtained, it can be directly used as a coating powder for electrostatic spraying of a substrate; it can also be prepared into a slurry and then used to coat the substrate.

[0073] The third aspect of the present invention provides the use of the above-mentioned coating or the coating prepared by the above-mentioned preparation method in coating of metal substrates.

[0074] The present invention applies the obtained coating to metal substrate coating, and the formed coating has the characteristics of high density, good adhesion to the metal substrate, and good tolerance in high humidity and high heat environment, and can meet the application requirements of complex, harsh and extreme environments such as high humidity and high heat.

[0075] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy, such as tinplate, titanium alloy, stainless steel, and the like.

[0076] A fourth aspect of the present invention provides an anti-corrosion coating, wherein the above-mentioned coating or the coating prepared by the above-mentioned preparation method is uniformly coated on the surface of a metal substrate, and the anti-corrosion coating is obtained after curing.

[0077] The anti-corrosion coating provided by the present invention is obtained by coating the aforementioned coating, and therefore also has the technical effects of the coating described above. The present invention applies the aforementioned coating to a metal substrate, and the formed coating has the characteristics of high density, good adhesion to the metal substrate, and good tolerance in a high humidity and high heat environment, and can meet the application requirements of complex, harsh and extreme environments such as high humidity and high heat.

[0078] In some embodiments of the present invention, the coating powder can be electrostatically sprayed onto the surface of the metal substrate; the coating can also be prepared into a slurry, and then evenly coated on the surface of the metal substrate by scraping, spin coating or spraying, and then cured to obtain the anti-corrosion coating. The coating method can be a conventional method in the art, which is not limited here. The curing method can be a conventional method in the art, such as heating curing, which is not limited here.

[0079] In some embodiments of the present invention, the thickness of the anti-corrosion coating is 100-500 μm, preferably 200-500 μm, and more preferably about 250 μm.

[0080] A fifth aspect of the present invention provides a coated product, comprising a metal substrate and the above-mentioned coating or the coating prepared by the above-mentioned preparation method coated on the metal substrate.

[0081] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy, such as tinplate, titanium alloy, stainless steel, and the like.

[0082] A sixth aspect of the present invention provides the use of the above-mentioned paint or the above-mentioned anti-corrosion coating in the fields of home appliance manufacturing, aerospace, and automobile manufacturing.

[0083] In some embodiments of the present invention, household appliances include refrigeration appliances (such as household refrigerators, cold drink machines, etc.), air conditioners (such as room air conditioners, electric fans, ventilation fans, hot and cold air blowers, air dehumidifiers, cold air blowers, humidifiers, etc.), cleaning appliances (such as washing machines, dryers, electric irons, vacuum cleaners, floor waxers, sweeping robots, etc.), kitchen appliances (such as electric stoves, microwave ovens, induction cookers, electric ovens, rice cookers, dishwashers, food processors, etc.), electric heating appliances (such as space heaters), audio and video appliances (such as micro projectors, televisions, radios, tape recorders, video recorders, cameras, combination stereos, etc.).

[0084] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0085] Example 1

[0086] The invention relates to a method for preparing a coating powder. The coating powder is prepared by mixing 76 parts of E51 epoxy resin, 27 parts of F51 epoxy resin, 46 parts of AFG-90 epoxy resin, 40 parts of bisphenol A phthalonitrile resin and 1 part of benzoin by weight, and then curing the mixture at 100-230°C for 15 minutes and at 230-280°C for 15 minutes under an inert atmosphere, followed by grinding and sieving to obtain a coating powder. The coating powder is poured into an electrostatic spray fluidizing barrel, sprayed with tinplate as a metal substrate, and then thermally cured at 230°C in an air environment for 15 minutes to form a final coating.

[0087] The thickness of the coating is 250 μm.

[0088] Example 2

[0089] The difference from Example 1 is that the coating formula is different. In this example, by weight, 53 parts of E20 epoxy resin, 15 parts of NPCN-704 epoxy resin, 41 parts of AG-601 epoxy resin, 30 parts of isophthalonitrile resin, and 0.1 parts of benzoin are used. Other parts are the same as in Example 1.

[0090] Example 3

[0091] The difference from Example 1 is that the coating formula is different. In this example, by weight, 96 parts of E44 epoxy resin, 33 parts of F51 epoxy resin, 50 parts of AG-80 epoxy resin, 50 parts of liquid phthalonitrile resin, and 10 parts of benzoin are used. The rest is the same as Example 1.

[0092] Comparative Example 1

[0093] The difference from Example 1 is that the coating formula is different. In this example, by weight, 27 parts of F51 epoxy resin, 46 parts of AFG-90 epoxy resin, 40 parts of bisphenol A type phthalonitrile resin, and 1 part of benzoin are used, and bisphenol A type epoxy resin is not contained. Other parts are the same as Example 1.

[0094] Comparative Example 2

[0095] The difference from Example 1 is that the coating formula is different. In this example, by weight, 76 parts of E51 epoxy resin, 46 parts of AFG-90 epoxy resin, 40 parts of bisphenol A type phthalonitrile resin, and 1 part of benzoin are used, and no phenolic epoxy resin is contained. Other parts are the same as in Example 1.

[0096] Comparative Example 3

[0097] The difference from Example 1 is that the coating formula is different. In this example, by weight, 76 parts of E51 epoxy resin, 27 parts of F51 epoxy resin, 40 parts of bisphenol A type phthalonitrile resin, and 1 part of benzoin are used, and no hyperbranched epoxy resin is contained. Other parts are the same as Example 1.

[0098] Comparative Example 4

[0099] The difference from Example 1 is that the coating formula is different. In this example, by weight, 76 parts of E51 epoxy resin, 27 parts of F51 epoxy resin, 46 parts of AFG-90 epoxy resin, 40 parts of boron trifluoride-ethylamine complex, and 1 part of benzoin are used, and phthalonitrile resin is not contained. Other parts are the same as Example 1.

[0100] Comparative Example 5

[0101] The difference from Example 1 is the curing method. In this example, the temperature is gradually increased from 80 to 100° C. for 30 minutes. The other aspects are the same as in Example 1.

[0102] Comparative Example 6

[0103] The difference from Example 1 is the curing method. In this example, the temperature is gradually increased from 300 to 350° C. for 30 minutes. The other aspects are the same as Example 1.

[0104] Comparative Example 7

[0105] The difference from Example 1 is that tinplate is used as the test sample and the surface is not covered with a protective coating.

[0106] Comparative Example 8

[0107] The difference from Example 1 is that tinplate is used as the test sample, the surface of which is sprayed with phthalonitrile powder, and then cured at 400° C. for 1 hour. The thickness of the cured coating is 250 μm.

[0108] Test Case

[0109] The epoxy resin coating cured by phthalonitrile in Example 1 was subjected to DSC testing, starting at 0°C and heating to 300°C at a rate of 10K / min. The DSC spectra of the epoxy resin coating cured by phthalonitrile in Example 1 before and after curing are shown in FIG. Figure 1-2 As shown in the figure, above the ordinate is exothermic, and it is found that it melts above 50°C, the solidification peak is at 230°C, the glass transition temperature is above 180°C, and the initial decomposition temperature is above 365°C.

[0110] The FTIR spectra of the epoxy resin coating cured by phthalonitrile in Example 1 before and after curing are as follows: Figure 3-4 As shown. Figure 3-4 It can be seen that before and after the curing of the epoxy resin coating cured by phthalonitrile, the infrared peak of the cyanide group decreases and the infrared peak of the amine group increases, proving that phthalonitrile successfully cures the epoxy resin.

[0111] The TGA curves of the coating in Example 1 after curing in air atmosphere and argon atmosphere are as follows: Figure 5-6 As shown by Figure 5 It can be seen that the cured resin shows good thermal stability in an air environment below 300°C, with an initial decomposition temperature of 366°C and a residual amount of 0%. Figure 6 It can be seen that the initial decomposition temperature of the cured epoxy resin in an argon environment is increased to 386°C, and it exhibits excellent heat resistance when the temperature is less than 350°C, with a residual amount of 38%.

[0112] The pull-out strength of the coatings in Examples 1-2 of the present invention based on tinplate substrates was tested, and the testing standard was ISO4624: 2023. The pull-out strength of the coating in Example 1 based on the stainless steel substrate was 0.358 MPa, and the pull-out strength of the coating in Example 2 based on the tinplate substrate was 0.457 MPa, which proved that the coating formed by the coating had the characteristics of high density and strong adhesion.

[0113] The cross-scratch test was performed on Examples 1-3 and Comparative Examples 1-8 to evaluate the corrosion resistance of the coating. The method is: take the prepared coating samples, scratch the surface thereof, and the scratch size of the sample surface is consistent. Then, the coating samples are placed in a salt spray test box. After 7 days of salt spray test, the surface of the sample is tested. The test standard is GB / T 10125-2021. The results are shown in Table 1:

[0114] Table 1

[0115]

[0116]

[0117] The corrosion resistance of the anti-corrosion coating was evaluated through a scratch test, and it was found that there was no obvious change in the surface coating of Examples 1-3 before and after the experiment. Except for the corrosion of the exposed external substrate, there was no corrosion in other places, while the surface corrosion of Comparative Examples 1-3 had a tendency to spread to the coating area, indicating that the epoxy resin requires a reasonable ratio of bisphenol A epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin; Comparative Example 4 had a tendency for surface corrosion to spread to the coating area but it was milder than that of Comparative Examples 1-3, indicating that ordinary curing agents could not achieve the corresponding effect; the surface coating of Comparative Examples 5-6 fell off seriously, indicating that the gradient heating method of the present invention requires precise temperature control to ensure that the coating is completely cured and not over-cured; Comparative Example 7 had severe corrosion at the scratch point and the corrosion tended to spread outward, and Comparative Example 8 had severe coating shedding at the scratch point, and severe corrosion at the scratch point and the corrosion tended to spread outward.

[0118] The high temperature resistance and long-term corrosion resistance of Examples 1-3 and Comparative Examples 1-8 were accelerated by taking the coating samples, soaking them in 170°C hot water at 0.65MPa in a high temperature autoclave for 2 days, observing the surface of the samples and detecting their electrochemical impedance (test standard GB / T 39482-2020). The results are shown in Table 2:

[0119] Table 2

[0120]

[0121]

[0122] For the coatings prepared in the examples and comparative examples, the initial electrochemical impedance was 10^12Ω. After being immersed in 170℃ hot water at 0.652MPa in a high-temperature and high-pressure autoclave for 2 days, there was no obvious change in the surface coatings of examples 1-3, and the electrochemical impedance only dropped to 10^11Ω. The surface coatings of comparative examples 1-3, 4, and 5-6 all had bubbles to varying degrees, and the electrochemical impedance dropped to a minimum of 10^6Ω. The surface corrosion of comparative example 7 was severe, and the surface coating of comparative example 8 fell off and had no anti-corrosion effect.

[0123] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present application. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A coating, characterized in that: The raw material components of the coating include, by weight: 70 to 240 parts of epoxy resin composition and 1 to 100 parts of phthalonitrile resin; The epoxy resin composition comprises 20 to 100 parts of bisphenol A epoxy resin, 10 to 40 parts of novolac epoxy resin, and 40 to 100 parts of hyperbranched epoxy resin; The phthalonitrile resin is selected from at least one of bisphenol A phthalonitrile resin, isophthalonitrile phthalonitrile resin and liquid phthalonitrile resin.

2. The coating according to claim 1, characterized in that The raw material components of the coating include, by weight: 105-185 parts of epoxy resin composition and 30-50 parts of phthalonitrile resin.

3. The coating according to claim 2, characterized in that The epoxy resin composition comprises 50 to 100 parts of bisphenol A epoxy resin, 15 to 35 parts of novolac epoxy resin and 40 to 50 parts of hyperbranched epoxy resin in parts by weight.

4. The coating according to claim 1 or 2, characterized in that: The bisphenol A type phthalonitrile resin is obtained by copolymerizing bisphenol A type phthalonitrile monomer, and the structural formula of the bisphenol A type phthalonitrile monomer is: And / or, the isophthalonitrile resin is obtained by copolymerization of isophthalonitrile monomers, and the structural formula of the isophthalonitrile monomers is: And / or, the liquid phthalonitrile resin is obtained by copolymerization of liquid phthalonitrile monomer, and the structural formula of the liquid phthalonitrile monomer is:

5. The coating according to claim 1, 2 or 3, characterized in that: The bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, E20 epoxy resin and E12 epoxy resin.

6. The coating according to claim 1, 2 or 3, characterized in that: The phenolic epoxy resin is selected from at least one of F51 epoxy resin and NPCN-704 epoxy resin.

7. The coating according to claim 1, 2 or 3, characterized in that: The hyperbranched epoxy resin is selected from at least one of AFG-90 epoxy resin, AFG-90H epoxy resin, AG-80 epoxy resin, AG-70 epoxy resin, AG-601 epoxy resin and AG-602 epoxy resin.

8. The coating according to claim 1, 2 or 3, characterized in that: The raw material components of the coating further include: 0.1 to 100 parts of filler by weight.

9. The coating according to claim 8, characterized in that The filler is selected from at least one of carbon black, graphite, carbon nanotubes, activated carbon, alumina, silica, mica, boron nitride, calcium silicate, benzoin, titanium dioxide, MXene, glass microspheres, quartz sand, iron powder, iron salt, cobalt chloride, nickel chloride, ferric oxide, ferrous oxide, cobalt oxide, nickel oxide, sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate and calcium phosphate.

10. A method for preparing a coating according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: mixing raw materials according to weight components, heating and solidifying them, and grinding and screening them to obtain epoxy resin sintered powder.

11. The preparation method according to claim 10, characterized in that: The heating and curing process is: heating to 100-280° C. and curing for 15-60 minutes.

12. The preparation method according to claim 11, characterized in that: The heating curing process is a gradient temperature rise curing process, which includes two stages: heating to 100-230° C. for curing for 15-30 min, and then heating to 230-280° C. for curing for 15-30 min.

13. Use of the coating according to any one of claims 1 to 9 or the coating prepared by the preparation method according to any one of claims 10 to 12 in coating a metal substrate.

14. An anti-corrosion coating, characterized in that: The coating according to any one of claims 1 to 9 or the coating prepared by the preparation method according to any one of claims 10 to 12 is uniformly coated on the surface of the metal substrate, and the anti-corrosion coating is obtained after curing.

15. A coated product, characterized in that The invention comprises a metal substrate and a coating as claimed in any one of claims 1 to 9 or a coating prepared by the preparation method as claimed in any one of claims 10 to 12, which is coated on the metal substrate.

16. The coated product according to claim 15, characterized in that The metal substrate includes a single metal or a metal alloy.

17. Use of the coating according to any one of claims 1 to 9 or the anti-corrosion coating according to claim 14 in the fields of home appliance manufacturing, aerospace, and automobile manufacturing.

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